In recent years, advances in computer technology have led to the development of digitation technologies also in the field of diagnostic imaging. X-ray imaging (roentgenography) is also performed for ascertaining dental condition in dental treatment, and in this includes panoramic imaging for imaging overall dentition and digital imaging for imaging part of the dentition. In digital imaging, an X-ray film is inserted into the patient's oral cavity, X-rays are directed from outside the patient through the teeth onto a CT or X-ray film, the X-ray film on which teeth were imaged is thereafter developed, converted to digital with a scanner or the like, taken into a computer, and displayed on the screen to observe the imaged X-ray image of the teeth.
In digital imaging for imaging part of the dentition, the sensor of an X-ray imager is inserted directly into the oral cavity, X-rays are directed from outside the patient through the teeth to take the tooth image data directly into a computer and display it to observe an X-ray image of the imaged tooth or teeth.
This digital imaging immediately offers speed and accuracy of examination and treatment and simultaneously enables acquisition of data for highly accurate diagnosis and treatment. Moreover, there are also advantages from the fact that the data is easy to process and analyse, that a method not using X-ray film can be adopted, and, in addition, that X-ray exposure can be markedly reduced.
A CCD (charged coupled device) sensor or CMOS (complementary metal oxide semiconductor) sensor is ordinarily used as the sensor of the intraoral digital X-ray imager, but for obtaining an accurate image of the periodontium, including the root, and the crown, it is necessary to perform imaging with the front of the sensor positioned and fixed vertically in close contact with these portions.
Owing to the need to capture an imaged region of the largest size and highest definition possible, the sensor of the intraoral digital X-ray imager and the periapical region and bitewing region must be accurately brought into close proximity. On the other hand, a sensor unit is inserted into the oral cavity of the patient, so that the cooperation of the patient must be obtained to open the mouth widely around the sensor and maintain a stationary condition. It is therefore necessary for the utilized instruments and the like to have shapes and material properties that do not cause distress. This is particularly important in cases where the patient overreacts to discomfort or tends to experience irritation inside the mouth.
Although dental imaging, which typifies X-ray imaging in dentistry, is utilized at high frequency, it was only recently digitized, and owing to the fact that a film is placed in the oral cavity as mentioned above, it involves issues that hamper widespread use, not only in the mechanical technical aspects related to imaging but also in the points of the environment making film fixing difficult and of the cooperation of the patient being hard to obtain.
In intraoral digital X-ray imaging, the positioning of the imager sensor and of the tooth periapical region and bitewing region is important, but there is a problem in that a high-definition image of the desired region cannot be captured unless patient distress and discomfort are eliminated to the utmost possible.
The sensor of the intraoral digital X-ray imager is inserted into the oral cavities of many patients for use. In order to prevent infection, a thin sheet-like vinyl or thin sheet-like foam soft resin is utilized as a cover that is disposably used and treated. However, intraoral digital X-ray imager sensors are often made of a hard resin or metal, material, so that with the conventional thin sheet-like cover, it is found, among other problems, that the patient is made to feel distress or discomfort because when the sensor is inserted into the patient's oral cavity and brought into close contact with the dentition, its corners strike against the patient's teeth, gums and other tissue, and the sheet is slippery, which makes placement very difficult and accurate imaging hard to achieve.
Although the instruments have been enhanced in performance and reduced in size, the hard imaging sensor is inserted into the irregularly shaped oral cavity, so that patient complaints of discomfort are frequent, while adoption of the intraoral digital system has not spread widely owing to the difficulty of imaging, and there are cases in which a purchaser of a recent sensor nevertheless hesitates to use it. Although technologies have been developed with consideration to ease and convenience of imaging and prevention of infection, many issues remain with regard to sensors and imaging methods that reflect the patient's viewpoint.
In order to overcome these problems, the idea emerged of covering the sensor itself with a flexible buffer means, and the method of covering it with a thin sheet of vinyl or the like that can be used disposably has been adopted. While this method mitigates the distress from insertion of a hard sensor into the oral cavity, a desire has been felt for the development of a buffer that overcomes such drawbacks as that the fitting of the buffer means on the sensor is troublesome and the fitting of a cover separate from the buffer means takes time, and that the buffer means increases the size of the sensor, making it difficult to eliminate the unnatural feel and sense of discomfort toward insertion into the oral cavity.